Reti trofiche fluviali e decomposizione biologica in un ecosistema urbano: Roma
Author(s)
D'Ayala, Antonio
Date Issued
February 10, 2011
Type
Doctoral Thesis
Abstract
The lotic ecosystem is often the output environment of the waste products generated by the urban ecosystem
metabolism. The impact of sewage water on the river may exceed his natural capacity of bio – assimilation.
when this happens there is a deterioration in the structure of the detritivorous community
and ecosystem function exercised by them: the natural decomposition of organic matter in the river.
In the present study was assessed the state of the community structure of macroinvertebrates colonizing the
detritus and the speed of degradation of the river plant debris as indicators of the self purification efficiency
in the Tiber River in Rome.
The experimental hypothesis was to verify the complete treatment of municipal wastewater from sewage
treatment plants and therefore the absence of a negative impact on the river ecosystem.
For this purpose were selected monitoring stations upstream and downstream of the two water treatment
plants, Rome- North and Rome -South, located at the ends of the stretch of urban river crossing.
The study was divided into the following phases:
- two campaigns to collect biological and chemical-physical data, in winter 2007 and summer 2008, to
highlight the seasonal differences;
- laboratory investigation on detritivore community at the population level, including interactions of
predation and competition, the characterization of food webs using stable isotopes 13C e 15N analysis (S.I.A.),
microfungal study of colonization and the rate of decomposition of leaf material belonging to Arundo donax
L .
The results indicate that the waste from water treatment plants alter the ecological structure at the base of
detritus processing and decrease the self –purification efficiency.
There was significative differences between upstream and downstream to the abundance of populations, the
diversity, the parameters of ecological niche, the complexity of trophic networks and the diversification of
food resources at their base. The rate of decomposition and stability of resilience (May, 1972) suffer from a
negative effect of urban wastewater, most evident during the summer and downstream of the sewage
treatment plant south of Rome.
Additional information
Dottorato di ricerca in Ecologia e gestione delle risorse biologiche
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